Web Mining ed Analisi

Transcript

1 Web Mining ed Analisi delle e Reti Sociali Introduzione all Analisi delle Reti Sociali Dino Pedreschi Dipartimento di Informatica Università di Pisa October 7, 2008 Data Mining: Concepts and Techniques 1

2 Materiale ae aedda didattico Slides by Jiawei Han, Univ. of Illinois at Urbana- Champaign M. E. J. Newman, The structure and function of complex networks, SIAM Review, Vol. 45, p , Chapter 9.2 of the book: Jiawei Han and Micheline Kamber. Data Mining: i Concepts and Techniques, 2nd ed. Morgan Kaufmann Publishers, Consultazione: Duncan J. Watts. Six Degrees: The Science of a Connected Age. (Norton, October 7, New 2008 York, 2003). Data Mining: Concepts and Techniques 2

3 Social Network Analysis Social Network Introduction Statistics and Probability Theory Models of Social Network Generation Networks in Biological System Mining on Social Network Summary October 7, 2008 Data Mining: Concepts and Techniques 3

4 Society Nodes: individuals Links: social relationship (family/work/friendship/etc.) S. Milgram (1967) John Guare Six Degrees of Separation Social networks: Many individuals with diverse social interactions between them. October 7, 2008 Data Mining: Concepts and Techniques 4

5 Social networks: Actor Connectivity Days of Thunder (1990) Far and Away (1992) Eyes Wide Shut (1999) Nodes: actors Links: cast jointly N = 212,250 actors k = P(k) ~k -γ γ=2.3 October 7, 2008 Data Mining: Concepts and Techniques 5

6 Social networks: Sex-Web Nodes: people (Females; Males) Links: sexual relationships 4781 Swedes; 18-74; 59% response rate. Liljeros et al. Nature 2001 October 7, 2008 Data Mining: Concepts and Techniques 6

7 Information networks: Science Citation ti Index 25 Nodes: papers Links: citations 1736 PRL papers (1988) Witten-Sander PRL P(k) ~k -γ (γ =3) (S. Redner, 1998) October 7, 2008 Data Mining: Concepts and Techniques 7

8 Information network: Science Coauthorship hi Nodes: scientist (authors) Links: write paper together (Newman, 2000, H. Jeong et al 2001) October 7, 2008 Data Mining: Concepts and Techniques 8

9 Communication networks The Earth is developing an electronic nervous system, a network with diverse nodes and links are -computers -routers -satellites -phone lines -TV cables -EM waves Communication networks: Many non-identical components with diverse connections between them. October 7, 2008 Data Mining: Concepts and Techniques 9

10 Tech. networks: Internet Backbone Nodes: computers, routers Links: physical lines (Faloutsos, Faloutsos and Faloutsos, 1999) October 7, 2008 Data Mining: Concepts and Techniques 10

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12 Complex systems Made of many non-identical elements connected by diverse interactions. BIOLOGICAL NETWORKS October 7, 2008 Data Mining: Concepts and Techniques 12

13 Biological networks: Food Web Nodes: trophic species Links: trophic interactions R. Sole (cond-mat/ ) R.J. Williams, N.D. Martinez Nature (2000) October 7, 2008 Data Mining: Concepts and Techniques 13

14 Natural Networks and Universality Consider many kinds of networks: social, technological, business, economic, content, These networks tend to share certain informal properties: large scale; continual growth distributed, organic growth: vertices decide who to link to interaction restricted to links mixture of local and long-distance connections abstract notions of distance: geographical, content, social, Do natural networks share more quantitative universals? What would these universals be? How can we make them precise and measure them? How can we explain their universality? This is the domain of social network theory Sometimes es also referred e ed to as link analysis ayss October 7, 2008 Data Mining: Concepts and Techniques 14